I feel like the most enjoyable part of old Saryn was to have so many damage numbers popping up across the screen at the same time because of the nature of how Spores spread. As it stands, it feels a little bit off that it doesn't spread anywhere near as much even with 280% range, even more so with the inability to recast it on other enemies without removing it from those currently suffering from it it, but I also understand the trepidation about making it too strong, seeing as it does have the potential to be so.
Maybe allow the Spores to spread like they used to but tone down the damage and the damage scaling a bit? That way it relies on there being a lot of enemies around for the Spores to tick up for the scary damage numbers, but it allows the Corrosive Procs to really shine and encourage players to do more than just stand still and let Spores do all of the work whilst still having the whole "Numbers Confetti" that Saryn used to enjoy across the entire map.
As it stands, I do really like the Molt change and the Miasma change. Definitely helps with the survivability of her and the mass Viral proc is much handier as a one off explosion than the old Corruption proc. It's not the most exciting ultimate in Warframe, but it's much more effective and that's what matters.
I feel Toxic Lash could be a little bit more buffed, again, maybe lower the damage of the amp but allow her team to benefit from it as well to help her fit the niche of "AoE DoT Utility" and to contribute to the number confetti again for everyone, so that people really know they've got a Saryn on their team. Letting everyone be capable of stacking Toxic procs on enemies from their weapons would be thematic to the frame and help solidify her niche of being THE large area threat that increases over time rather than just an outright immediate damage buff from the likes of Rhino and sorts.
As it stands though, I feel like with a few quality of life tweaks and changes it could be a really successful rework to literally my favourite frame in the game. ❤️